#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int main()
{
	int arr[10] = { 0 };
	int sum = 0;
	for (int i = 0; i < 10; i++)
	{
		scanf("%d ", &arr[i]);
		sum += arr[i];
	}
	double ret = sum * 1.0 / 10;
	printf("%lf ", ret);
	return 0;
}